Method for Generating Superheated Steam

ABSTRACT

A method which develops a supercritical combustion chamber environment and combines fumigation and water conversion to superheated steam to effect greater fuel efficiency and reduce exhaust gas pollutants from a compression ignition engine. The invention utilizes the fumigant method by combining two gases (DME and heptane) which autoignite prior to the injection of the liquid water. This pre-combustion of the fumigant gases combined with the engine&#39;s compression of the combustion chamber gases is managed to attain a supercritical combustion chamber environment into which the liquid water is injected. This targeted supercritical combustion chamber environment causes the water to become a superheated steam, resulting in significantly greater efficiency and negligible exhaust gas pollutants resulting from the steam engine.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation in part of U.S. patentapplication Ser. No. 13/517,861, filed Jun. 12, 2012, which applicationclaims the benefit of the filing date of U.S. Provisional PatentApplication Ser. No. 61/496,887, filed Jun. 14, 2011. Each of theforegoing applications is incorporated by reference in its entirety asif fully set forth herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

TECHNICAL FIELD

The present invention relates generally to internal combustion engines,and more particularly to an improved method for generating asupercritical combustion chamber environment for compression ignitionengines.

BACKGROUND INFORMATION AND DISCUSSION OF RELATED ART

The inventor of the diesel engine, Rudolph Diesel—1897, used “naturalgas” as a diesel engine fumigant fuel charge. Fumigation of a dieselengine is the addition of a gaseous fuel to the intake air charge of adiesel engine. Development of diesel engine fumigation techniques hascontinued, such as that disclosed in Ritter et al. U.S. Pat. No.6,901,889.

The pre-heating of diesel fuel to improve combustion efficiency andreduce exhaust gas pollutants has been active since the 1930's.Hypergolic diesel combustion received significant attention in the1980's. More recently Tavlarides et al. U.S. Pat. No. 7,488,357 andothers disclose methods and apparatus which cause diesel fuel to becomesupercritical prior to injection into the combustion chamber.

U.S. Pat. No. 4,892,561 to Levine discloses fuels for internalcombustion engines which contain at least 50% by weight of methyl ether.

U.S. Pat. No. 5,632,786 to Basu et al. describes a method for operatinga spark ignition internal combustion engine utilizing an improvedcomposition containing dimethyl ether and propane as fuel.

U.S. Pat. No. 6,095,102 to Willi et al. teaches a dual fuel engine whichcreates a substantially homogeneous mixture of gaseous fuel, air, andpilot fuel during a compression stroke.

U.S. Pat. No. 6,145,495 to Whitcome discloses a propane injection systemfor a diesel engine.

U.S. Pat. No. 6,202,601 to Ouellette et al. describes a method andapparatus for dual fuel injection into an internal combustion engine. Amain fuel is ignited by a pilot fuel that is more readily flammable thanthe main fuel.

U.S. Pat. No. 6,206,940 to Weissman et al. teaches fuel formulations toextend the lean limit.

U.S. Pat. No. 6,213,104 to Ishikiriyama et al. discloses supplying fuelto an internal combustion engine in a supercritical state by raising thepressure and the temperature of the fuel above the critical pressure andtemperature.

U.S. Pat. No. 6,286,482 to Flynn, et al. describes a premixed chargecompression ignition engine with combustion control.

U.S. Pat. No. 6,324,827 to Basu et al. teaches a method of generatingpower in a dry low NOx combustion system.

U.S. Pat. No. 6,607,567 to Towfighi discloses propellant gas for toolsoperated by combustion power on the basis of combustible gasescontaining a mixture of 40% to 70% by weight of dimethyl ether, nitrousoxide and/or nitromethane, 8% to 20% by weight of propylene, methylacetylene, propane and/or propadiene and 20% to 45% by weight ofisobutane and/or n-butane.

U.S. Pat. Nos. 6,901,889 and 7,225,763 to Ritter, et al. describes asystem and method to reduce particulate and NOx emissions from dieselengines through the use of a duel-fuel fumigation system.

U.S. Pat. No. 7,488,357 to Tavlarides, et al. teaches a composition ofdiesel, biodiesel or blended fuel with exhaust gas mixtures or withliquid CO2. The composition is in a liquid state near the supercriticalregion or a supercritical fluid mixture such that itquasi-instantaneously diffuses into the compressed and hot air as asingle and homogeneous supercritical phase upon injection in acombustion chamber.

The foregoing patents reflect the current state of the art of which thepresent inventor is aware. Reference to, and discussion of, thesepatents is intended to aid in discharging Applicant's acknowledged dutyof candor in disclosing information that may be relevant to theexamination of claims to the present invention. However, it isrespectfully submitted that none of the above indicated patentsdisclose, teach, suggest, show, or otherwise render obvious, eithersingly or when considered in combination, the invention described andclaimed herein.

SUMMARY OF THF INVENTION

The method for supercritical diesel combustion of the present inventioncombines fumigation and supercritical diesel fuel combustion to effectgreater fuel efficiency and reduce exhaust gas pollutants from acompression ignition engine such as a diesel engine. The inventionutilizes the fumigant method by combining two gases (DME and propane)which autoignite prior to the injection of the liquid diesel fuel. Thispre-combustion of the fumigant gases combined with the engine'scompression of the combustion chamber gases is managed to attain asupercritical combustion chamber environment into which the liquiddiesel fuel or water is injected. This targeted supercritical combustionchamber environment causes the diesel fuel to become a supercriticalfluid prior to combustion (or the water to become a superheated steam),resulting in significantly greater efficiency and negligible exhaust gaspollutants resulting from the combustion of the diesel fuel.

Fumigation of a diesel engine air intake charge with a combustiblegaseous fuel has always required that the injected liquid diesel fuel bethe pilot ignition source initiating the combustion event. This allowedfor accurate timing of the combustion event, reduction of the totaldiesel fuel consumed, and reduction of exhaust gas pollutants becausethe gaseous fuel combusts much more completely than the liquid dieselfuel.

Combustion of diesel fuel as a supercritical fluid causes the combustionevent to resemble a gaseous fuel combustion event. As a supercriticalfluid diesel fuel does not exhibit surface tension and has a diffusiontwo magnitudes greater than as a liquid. These are the two mainproperties of a supercritical fluid which contribute to greatercombustion efficiency and lower exhaust gas pollutants.

Liquid diesel fuel is injected into the combustion chamber by very highpressure to effect atomization of this liquid fuel. The result is aspray composed of droplet and ligaments entering into the combustionchamber environment. There is an ignition delay time period as theliquid fuel droplets and ligaments take on heat from the combustionchamber gases and commence to vaporize. It is this diesel fuel vaporwhich combusts. Diesel combustion is generally considered to be a leancombustion event but this is only true when looking at the bulk numberrelationship for the fuel and the oxidant. Each droplet and ligamentcreates a very fuel rich combustion zone surrounding their surface.These rich combustion zones create “prompt” NOx (nitrogen compoundsformed during elevated temperature combustion events and during fuelrich combustion) and encapsulate the remaining liquid within the dropletor ligament in a zone of extreme heat which creates pyrolysis and cokingof the remaining fluid. The source of particulates in the exhaust gasand temperature created NOx.

As a supercritical fluid diesel fuel does not exhibit surface tension,therefore droplets and ligaments cannot form, or if formed cannot remainformed. This excludes the possibility of fuel rich combustion zones,reducing the production of both prompt and thermal NOx as well as thepyrolysis and coking of the diesel fuel.

The companion effect of the loss of surface tension is that the dieselfuel now has 100 times greater diffusivity than as a liquid droplet orligament. The combustion effect is that the diesel fuel is now at least100 times more in contact with the oxidant. The result is a combustionevent that releases more heat energy in a shorter period of time than atypical diesel combustion without the formation of prompt NOx andparticulates.

In a further embodiment, water is injected instead of diesel fuel tocreate steam. The supercritical environment created in the cylinder isused to transfer heat directly to the water to generate superheatedsteam, this gas expansion is the principle driving force acting upon thepiston. The efficient capture of heat and low heat loss creates a highlyefficient steam driven engine.

It is therefore an object of the present invention to provide a new andimproved supercritical combustion chamber environment for compressionignition engines such as diesel engines.

It is another object of the present invention to provide a diesel enginecombustion chamber environment with improved fuel efficiency.

A further object or feature of the present invention is a diesel enginecombustion chamber environment with reduced NOx and soot emissions.

A further object of this embodiment for fumigant charged internalcombustion engine (ICE) is to increase efficiency by capturing the heatof the combustive fumigant fuel before there is significant loss of thisheat into the coolant system of the engine or be released to theatmosphere, and converting it into steam.

Other novel features which are characteristic of the invention, as toorganization and method of operation, together with further objects andadvantages thereof will be better understood from the followingdescription considered in connection with the accompanying drawings, inwhich preferred embodiments of the invention are illustrated by way ofexample. It is to be expressly understood, however, that the drawingsare for illustration and description only and are not intended as adefinition of the limits of the invention. The various features ofnovelty which characterize the invention are pointed out withparticularity in the claims annexed to and forming part of thisdisclosure. The invention resides not in any one of these features takenalone, but rather in the particular combination of all of its structuresfor the functions specified.

There has thus been broadly outlined the more important features of theinvention in order that the detailed description thereof that followsmay be better understood, and in order that the present contribution tothe art may be better appreciated. There are, of course, additionalfeatures of the invention that will be described hereinafter and whichwill form additional subject matter of the claims appended hereto. Thoseskilled in the art will appreciate that the conception upon which thisdisclosure is based readily may be utilized as a basis for the designingof other structures, methods and systems for carrying out the severalpurposes of the present invention. It is important, therefore, that theclaims be regarded as including such equivalent constructions insofar asthey do not depart from the spirit and scope of the present invention.

Further, the purpose of the Abstract is to enable the U.S. Patent andTrademark Office and the public generally, and especially thescientists, engineers and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. The Abstract is neither intended to define theinvention of this application, which is measured by the claims, nor isit intended to be limiting as to the scope of the invention in any way.

Certain terminology and derivations thereof may be used in the followingdescription for convenience in reference only, and will not be limiting.For example, words such as “upward,” “downward,” “left,” and “right”would refer to directions in the drawings to which reference is madeunless otherwise stated. Similarly, words such as “inward” and “outward”would refer to directions toward and away from, respectively, thegeometric center of a device or area and designated parts thereof.References in the singular tense include the plural, and vice versa,unless otherwise noted.

BRIEF DESCRIPTION OF THF DRAWINGS

The invention will be better understood and objects other than those setforth above will become apparent when consideration is given to thefollowing detailed description thereof. Such description makes referenceto the annexed drawings wherein:

FIG. 1 is a cross sectional view of a two-stroke engine with the pistonin the neutral exhaust/intake position;

FIG. 2 is a cross sectional view of the engine at the beginning of thecompression stroke; and

FIG. 3 is a cross sectional view of the engine at the beginning of thepower stroke.

DETAILED DESCRIPTION OF THF INVENTION

This invention applies to all compression ignition engines (CIE) whichoperate on diesel fuel No. 2, light fuel oil, biodiesel, wateremulsified diesel fuels, water, steam or blends of diesel surrogates,light fuel oil emulsions, or blends of these fuels. This invention canbe readily retrofitted onto existing CIE with only slight modificationbetween installations on two-stroke and four-stroke CIE. This inventioncan also be readily implemented into new CIE design and construction.The apparatus and method will change dependent on the “family of CIE” towhich it is applied. “Family of CIE” is intended to categorize asfunctional inclusionary units similar CIE. The broadest category is thedivision between two and four-stroke CIE. The method and apparatus willvary when adopted for use on the different families of CIE. Rotationalspeed, low, medium, high will be subfamilies, as will displacementvolume of the combustion chamber.

The principle of this novel combustion method will remain the same. Thisprinciple is the use of a fumigant fuel blend to establish asupercritical fluid/gas environment within the combustion chamber of theCIE prior to the injection of the liquid diesel fuel. This supercriticalfluid/gas environment has a target pressure of not less than 800 psibeing expressed in the constant volume space (CVS) of the combustionchamber prior to the injection of the liquid diesel fuel. CVS isgenerally accepted to be the combustion space compressed by the pistoncommencing at 10° BTDC (before top dead center, the position of thepiston prior to reaching TDC) and ending at 10° ATDC (after top deadcenter, the position of the piston after passing TDC). To achieve thispressure and corresponding temperature, 1,200° F. to 1,400° F., thecomponents of the inventive method and apparatus will be adapted toperform for each family of CIE. The following detailed description is anembodiment of this invention as applied to a two-stroke uniflow mediumspeed CIE with a displacement of greater than 500 cubic inches percylinder. The diesel fuel is injected by mechanical unit injectors.

This type of CIE utilizes either a Roots blower or a turbo charger tocompress intake air into air chambers surrounding the lower portion ofthe cylinder assemblies, which comprise these engines power assemblies.These air boxes have access doors to which the fumigant fuel injectorwill be affixed and aimed at the nearest air intake port supplying thecylinder. This injector will inject liquid fumigant fuel supplied to itby a pressure vessel fuel tank which has an internal fuel pump to boostthe tank pressure so that the fuel will remain liquid throughout itsroute to the injector. The pulse of the injector will be controlled by adevice, which, at a minimum, constantly monitors the following engineparameters: the engine rpms to establish a timing sequence for theindividual injection pulse, to be timed to pulse just as the intakeports are revealed by the piston and the air charge begins to enter thecombustion chamber; and the continuous reading of the individual (e.g.,every fourth cylinder) pressure developed during the entire enginecycle. This precise pressure information will be interpreted by acontroller, which in turn will vary the fumigant fuel injector pulseduration to provide more or less fumigant fuel to the combustionchamber. The target is 800 psi being expressed in the CVS prior to theinjection of the diesel fuel. At 800 psi and the relative temperature,1,200° F. to 1,400° F., over 90% of the gases in the CVS aresupercritical. H2O and CO2 will not be supercritical but N2, O2, OH,H2O2, and CO will all be supercritical.

The unit injector for the diesel fuel will be modified to inject thediesel fuel after TDC, e.g., 5° to 10° ATDC. The pulse duration of theunit injector will also be shortened. Because the atomized spray of thediesel fuel will encounter significantly higher combustion chamberpressure it will suffer greater shear force, greatly reducing the sizeof the diesel fuel droplets and ligaments. At the same time thesedroplets and ligaments will be innervated by the supercriticalfluids/gases, which comprise the supercritical combustion chamberenvironment. As supercritical fluid/gases these substances becomehyper-solvents.

The highly atomized diesel fuel droplets and ligaments are not onlyheated from the outside but also from the inside by both conduction andradiation. Supercritical substances release over 60% of their heatenergy as radiant energy. At 800 psi the vaporization is delayedsufficiently to allow the combustion chamber supercritical environmentto impart enough heat energy to the diesel fuel such that it transitionsbeyond its critical temperature point prior to initiation of significantcombustion. The diesel fuel has already been pushed beyond its criticalpressure point by the injectors and sustained beyond this criticalpressure point by the pressure encountered in the combustion chamber.This transition beyond the critical temperature and pressure points hascaused the diesel fuel to become a supercritical fluid, without surfacetension and 100 times more dispersed into the supercritical combustionchamber environment. Combustion of the diesel fuel proceeds much moreenergetically than typical diesel fuel combustion and later in therotation cycle of the CIE.

Typical diesel fuel combustion is timed for maximum heat release tooccur in the CVS. The combustion event typically initiates just prior tothe piston achieving 10° BTDC and continues to its high heat releasethru 10° ATDC. Functionally from the combustion point of view, thissequence allows the diesel fuel to be reasonably combusted prior to theretained heat in the combustion chamber dropping below the temperaturenecessary to support combustion, about 60° ATDC. From a mechanical andheat management perspective this timing is wasteful and contributes togreater formation of NOx compounds. Mechanically, timing high heatrelease when the piston relationship to the crankshaft is essentially avertical line is the time of lowest mechanical advantage and leastpossible transference of energy to aid in the rotation of thecrankshaft. This high heat release is essentially stalled for almost athird of its active combustion sequence. The effect of this stall is toallow the heat to sink into the most readily available heat sinks, N2and O2, 75% and 15% respectively of the combustion gases. This stallingof the combustion events mechanical transference and the companionsinking of heat into N2 creates CIE inefficiency and increased amountsof NOx in the exhaust gas.

In the inventive method, the combustion gases are supercritical whichallows the timing of the diesel fuel combustion event to be delayed to atarget of high heat release at 20° ATDC. At this crank angle thetransference of energy is more mechanically favorable and allows thecombustion chamber space to grow much more quickly than in typical CIEcombustion, thus relieving the peak heat sinking and formation ofsignificant NOx compounds.

This supercritical combustion chamber environment is created bycombining the compression of the combustion chamber gases with asequence of pre-diesel fuel injection combustion events. The fumigantfuel injected into the air intake is a blend, and preferably a customblend, blended for each CIE family, of propane and dimethyl ether (DME).These fuels are miscible and combined in a single pressure vessel,blended specifically for the CIE family being served, but have beendetermined to range from 1-20% DME and 80-99% propane. In this example,the fumigant fuel is injected as a liquid. In the case of highrotational speed CIE family of engines the fumigant fuel would beinjected as a gas for either two-stroke or four-stroke engines. Due tothe low boiling point of the fumigant fuel components (−44° F. forpropane and 11° F. for DME), these liquid fuels will vaporize in theearly stages of the compression stroke and quickly homogenize with theair charge as the compression of the charge gases increases. Atapproximately 20° BTDC the DME will autoignite. This autoignitiontriggers the ignition of the propane. The fumigant fuel combustion is atwo stage combustion so that the larger of the combustion events, thepropane combustion, occurs just as the CVS is being entered into. Thisis done to lessen the backpressure on the piston. The DME combustion isprincipally a means to trigger the propane combustion.

The combustion chamber pressure may be continuously read by anin-cylinder pressure sensor, e.g. one for every four cylinders. Thesensors output is interpreted by a controller, which increases ordecreases the pulse duration of the fumigant fuel injector to bestmanage the fumigant fuel flow into the combustion chamber, to attain thetarget supercritical pressure prior to the diesel fuel injection.

Referring now to FIGS. 1 through 3, wherein like reference numeralsrefer to like components in the various views, there is illustratedtherein a new and improved method for supercritical diesel combustion.

The drawing figures illustrate a cross sectional view of a uniflow,two-stroke diesel engine. The operating principles apply as well to afour-stroke diesel engine, the difference being that the fumigant fuelinjectors would be mounted on the four-stroke engines air intakemanifold as close to each cylinders intake valves as possible. Thefumigant fuel injector depicted is for application of the inventivesystem to existing diesel engines. Newly constructed engines couldimplement the system, optionally, by placing the fumigant fuel injectoras a direct injection component, pulsing directly into the combustionchamber.

FIG. 1 depicts a two-stroke diesel engine 10 with the piston 12 at thepoint in which the piston is in the neutral exhaust/intake position. Theexhaust valves 14 have opened just before the piston's descent whichreveals the air intake ports 16 to allow the exhaust gas from theprevious combustion to begin exiting thru the exhaust ports 18. As thepiston continues to descend it reveals the air intake ports 16, whichhave been pressurized by the air compressor 20. All diesel enginesoperating on diesel fuel utilize some form of air compressor, such as ablower or turbocharger, to force air into the combustion chamber of theengine. Fresh intake air floods into the combustion chamber aiding inpushing the exhaust gases from the previous combustion out through theexhaust ports. Just as the fresh air begins to enter the combustionchamber the fumigant fuel injector 22, which is mounted and aimeddirectly at one of the air intake ports, pulses, releasing a specificvolume of mixed fumigant fuel supplied by the fumigant fuel tank 24.

In low and moderate speed diesel engines (e.g., under 1200 rpm), thefumigant fuel will be injected as a liquid. High speed diesel engineswill have the fumigant fuel injected as a gas to assure that completevaporization and homogenization occurs prior to autoignition of thefumigant fuel. The fumigant fuel is a mixture of propane and dimethylether held in a common pressurized tank 24. Propane vaporizes at −44° F.and dimethyl ether vaporizes at −11° F., essentially both permanentgases at standard operating conditions.

FIG. 2 is a cross sectional view of the engine at the beginning of thecompression stroke. The piston 12 continues to rise, closing off the airintake ports 16, the exhaust valves 14 have closed, and the compressionstroke begins. As the piston slides towards the exhaust valves thecombustion chamber gases are compressed and begin to rise intemperature. All diesel engines are designed so that the compression ofthese gases will increase in temperature well beyond the autoignitiontemperature of diesel fuel, prior to the piston entering the CVS.Typical diesel fuel compression ignition occurs as the diesel fuel isinjected into the combustion chamber, initiating from approximately 16°BTDC. Operating with the inventive system the piston compresses thefumigant fuel air mixture 26 causing the fumigant fuel to vaporize andhomogenize with the air charge. At approximately 20° BTDC the dimethylether will have achieved autoignition temperature and combust. Thiscombustion will cause the propane to combust, which combined with thecompression of the gases by the piston, will result in a supercriticalcombustion chamber environment.

FIG. 3 is a cross sectional view of the engine at the beginning of thepower stroke, and the supercritical combustion chamber environment 32,with a CVS pressure of approximately 800 psi. At this pressure andcorresponding temperature, 1,200 to 1,400° F., all the gases in thecombustion chamber (except H2O and CO2) are supercritical fluids.Between 5° and 10° ATDC the diesel fuel from diesel fuel tank 28 isinjected into this supercritical environment through diesel fuelinjectors 30.

All diesel engines inject the diesel fuel at pressures 1,000's of psiabove the diesel fuel critical pressure point. Because the CVS pressureis approximately 800 psi, roughly 2.5 times the critical pressure pointof diesel fuel, the injected diesel fuel stays well above its criticalpressure point. This injected diesel fuel is subjected to very highshear forces because of the increased pressure of the CVS, whichincreases atomization of the diesel fuel droplets and ligaments. Theprinciple supercritical gases in the CVS are N2 and O2, which assupercritical fluids, act as hyper-solvents, innervating the diesel fueldroplets and ligaments thus imparting heat energy, over 60% as radiantenergy, from within the diesel fuel droplet and ligament as well as fromthe exterior. This action by the supercritical hyper-solvents impartsheat energy into the diesel fuel such that the diesel fuel transitionsinto a supercritical state prior to combustion.

As a supercritical fluid diesel fuel does not have surface tension andis dispersed 100 times greater than as a liquid within the supercriticalcombustion chamber environment. The initiation of combustion of thissupercritical diesel fuel is targeted to occur at 20° ATDC to takeadvantage of the maximum exertion of force at a time of greatestmechanical slider/crank leverage. Because the maximum heat release ofthe diesel fuel is now timed to take advantage of a much higher pistonspeed heat retention will be minimal and formation of NOx compounds willbe significantly reduced.

In-Situ Steam Embodiment to Supercritical Diesel Combustion Patent

Another embodiment of the application of this invention is the use ofthe combination fumigant fuels of DME and heptane to create asupercritical chamber environment to heat water into a superheatedsteam, the principle gas expansion working fluid (PWF) acting upon thepiston. Instead of having to inject a further combustible fuel such asglycerin or glycerin/water as shown in U.S. patent application Ser. No.14/188,739 on Feb. 25, 2014, now U.S. Pat. No. 9,297,299 entitled“Method for Superheated Glycerin Combustion” which describes thecombustion of a glycerin/water combination and is incorporated herein byreference, only water is added. Please note also that in the presentapplication, the hexane of the '299 patent is preferably replaced byheptane, but use of either gas is anticipated by this invention.

The combination of these fuels (DME and heptane) injected along with theair charge of an internal combustion two stroke diesel engine willresult in a two stage combustion process occurring prior to TDC. Using a16 tol compression engine, the combustion sequence will begin betweenthirty and twenty degrees BTDC and will have fully combusted prior tothe piston attaining TDC. As with the supercritical diesel combustionfumigant charge, the combustion space gases will in greater part becomesupercritical prior to the PWF being injected. The conditions of thecylinder after combustion and positioning of the piston with respect totop and bottom dead center (“TBC” and “BDC”) are provided above withrespect to the diesel injection embodiment and are reincorporated here.

In the case of this embodiment, the main injected working fluid isliquid water instead of diesel or other combustible fuel. The waterinjection will occur between TDC and ten degrees ATDC. The supercriticalgases already present in the combustion chamber will exchange theirenergy much quicker than the compressed air of the typical gases of acompression stroke air charge. The injected water instantly will becomesuperheated steam. The expansion of water into steam provides the motiveforce to move the piston outward. The steam will then exit the cylinderduring the exhaust stroke and may be recovered downstream, as is wellknown in the art. The use of steam obviates the need for other fuelssuch as diesel, though obviously the amount of power generated will beaffected by the replacement fluid.

In a typical internal engine combustion event, the majority (e.g., over60%) of the caloric value of the fuel is lost to the engine coolantsystem and to the heat of the exhaust gases. By staging a fumigant fuelpre-TDC combustion event and immediately following this combustion withwater injection, the heat normally lost to the cooling and exhaust gasesis retained (“absorbed”) in the phase change of the liquid water intosteam. The efficiency of the engine is greatly enhanced and as a furtherbenefit, the exhaust gases do not carry any significant amount ofnitrous oxide compounds, particulate, or carbon compounds.

The object of this embodiment for fumigant charged ICE is to increaseefficiency by capturing the heat of the combustive fumigant fuel beforeit can spread into the coolant system of the engine or be released tothe atmosphere, and capturing the heat by converting it into steam andusing the steam as a motive force.

The following description of this embodiment of supercritical fumigantcombustion relies upon a two-stroke, uniflow, compression ignitionengine design as depicted in FIGS. 1-3.

The fumigant fuel injector is a single hole direct injector placed atthe highest intake port of the uniflow engine aimed at the interior ofthe cylinder. The preferred fumigant fuel is a mixture of dimethyl ether(“DME”) and heptane, though gases other than heptane could be used asdescribed above. The DME is dissolved into the heptane in a ratio ofbetween 20/1 to 40/1 depending on what field of use the engine isemployed in and the engine size. This solution is retained in a pressuretank with sufficient pressure to keep the DME in the liquid state. Therail to the injectors is also kept at a pressure high enough to maintainthe DME in the liquid state.

The fumigant fuel charge is approximately one third of the typical fuelcharge required to support an ICE performance. The injection of thefumigant fuel is timed to occur just after bottom dead center (“BDC”) ofthe compression pistons travel and is swept into the now exposedcylinder cavity along with the intake air charge. Upon injection of thefumigant fuel the typically atomized droplets are further reduced as theDME immediately vaporizes and shatters the heptane/DME droplet, thusincreasing the overall surface area of the remaining heptane droplet.Essentially creating a homogenous charge within the compressed aircharge.

In a 16/1 compression engine, this homogenous charge will beginautoignition around 30 degrees BTDC and will have completed combustionat TDC. The resultant combustion chamber gases are now predominatelysupercritical. Because the fumigant fuel volume is never more than onethird of the typical volume required by an ICE (“Internal CombustionEngine”), the combustion of the fumigant fuel charge is both morecomplete and does not attain the temperature at which NOx is formed.This thus lowers carbon emissions and NOx.

The water injector is placed as typical for an ICE. Performance isenhanced if the water is preheated by heat extracted from the ICEexhaust gases. Preheating in this fashion reduces the amount of fumigantfuel applied and facilitates condensation of the steam exhaust which, inpart, reduces visual impact of the exhaust stream.

After TDC and before 10 degrees ATDC the water is injected into thesupercritical gases present in the combustion chamber. The atomizedwater droplets are innervated by the supercritical gases and instantlyabsorb the heat of these gases and become superheated steam. This is asingle step phase change reaction and is considerably faster than acombustion reaction. Also, the gas expansion ratio of water is greaterthan the expansion ratio of typical fuels. The result is significantlygreater torque and efficiency of the ICE. As the steam is superheated,its deposition on the metal surfaces of the combustion chamber isminimal. The steam expansion is used to drive the piston 12 outwardly.During the exhaust phase, the steam is expelled from the cylinder iscaptured and reused as necessary in processes well known in the art. Thepiston drives a crankshaft or other or other device such a lineargenerator. The cylinder then begins the intake cycle and repeats asnecessary.

The above disclosure is sufficient to enable one of ordinary skill inthe art to practice the invention, and provides the best mode ofpracticing the invention presently contemplated by the inventor. Whilethere is provided herein a full and complete disclosure of the preferredembodiments of this invention, it is not desired to limit the inventionto the exact construction, dimensional relationships, and operationshown and described. Various modifications, alternative constructions,changes and equivalents will readily occur to those skilled in the artand may be employed, as suitable, without departing from the true spiritand scope of the invention. Such changes might involve alternativematerials, components, structural arrangements, sizes, shapes, forms,functions, operational features or the like.

Therefore, the above description and illustrations should not beconstrued as limiting the scope of the invention, which is defined bythe appended claims.

What is claimed as invention is:
 1. A method for creating superheatedsteam comprising: providing a compression ignition engine having acombustion chamber and a piston slidably moveable within a portion ofsaid combustion chamber; providing a fumigant fuel charge to thecombustion chamber to autoignite and create a supercritical environmentin the combustion chamber prior to the injection of a water; injectingthe principle working fluid, water, into the combustion chamber, whereinthe water is converted to superheated steam after injection into thesupercritical environment in the combustion chamber; and saidsuperheated steam expands to force said piston outward.
 2. The methodfor superheated steam of claim 1, wherein the fumigant fuel chargecomprises a mixture of dimethyl ether and heptane.
 3. The method forsuperheated steam of claim 1 wherein the fumigant fuel charge comprises1-20% dimethyl ether and 80-99% heptane.
 4. The method for superheatedsteam of claim 1 wherein the step of providing a fumigant fuel chargecomprises injecting a fumigant fuel into an air intake port on theengine.
 5. The method for superheated steam of claim 4 wherein thefumigant fuel charge is injected as a liquid.
 6. The method forsuperheated steam of claim 4 wherein the fumigant fuel charge isinjected as a gas.
 7. The method for superheated steam of claim 1wherein the liquid water is injected into the combustion chamber aftertop dead center (“TDC”).
 8. The method for superheated steam of claim 1wherein the liquid water is injected into the combustion chamber at 5°to 10° ATDC.
 9. The method for superheated steam of claim 1 wherein thesupercritical environment has a constant volume space pressure of atleast 800 psi prior to the injection of the water.
 10. The method forsuperheated steam of claim 1 wherein the supercritical environment has atemperature of 1,200° F. to 1,400° F.
 11. A method for superheated steamcreation in a compression ignition engine, the method comprising:combining two gases which autoignite prior to the injection of water,wherein the two gases are dimethyl ether and heptane; managing thepre-combustion of the fumigant gases combined with the engine'scompression of the combustion chamber gases to attain a supercriticalcombustion chamber environment into which the water is injected andconverted to steam.
 12. A method for supercritical combustioncomprising: providing a compression ignition engine having a combustionchamber; providing a fumigant fuel charge to the combustion chamberconditioned to autoignite to create a supercritical environment in thecombustion chamber prior to the injection of a fuel, wherein said fuelis not the fumigant fuel; and injecting water into the combustionchamber after the chamber has been conditioned to a supercriticalenvironment, wherein the water is raised from a liquid to a superheatedsteam.
 13. The method for supercritical combustion of claim 12, whereinthe fumigant fuel charge comprises a mixture of dimethyl ether andheptane and wherein the fumigant fuel charge comprises 1-20% dimethylether and 80-99% heptane.
 14. The method for supercritical combustion ofclaim 12, wherein the step of providing a fumigant fuel charge comprisesinjecting a non-diesel fumigant fuel into an air intake port on theengine.
 15. The method for supercritical combustion of claim 12, whereinthe supercritical environment has a constant volume space of at least800 psi prior to the injection of the fuel and wherein the supercriticalenvironment has a temperature of 1,200 F to 1,400 F.